The invention pertains to a disk brake with full lining, and more particularly a fluid-pressure-operated full lining disk brake having an automatic slack adjusting device.
A disk brake of this type with an automatic adjusting device, which automatically compensates for any increase in stroke due to the wear of the brake linings, is known through U.S. Pat. No. 4,026,391, assigned to the assignee of the present invention.
For this known disk brake the frictional force interaction of the adjustments presents a problem, caused by the necessity that the adjusting members have to be moved either by a spring or by pressure in order to initiate an adjustment step, since as a result of dirt or corrosion the frictional forces may be so high as to render the adjusting members immobile, thus hindering or even preventing the automatic adjustment.
Another difficulty in connection with the already known disk brake adjusting device may be seen in the fact that an adjusting step may be initiated even with maximum piston stroke, making a large return stroke necessary. It has to be taken into account here that the adjustment in the event of a full braking action is being initiated with simultaneous maximum and thermal expansion of the housing. For this braking situation the return stroke has to be designed in such a way that it is great enough, so that when the elastic and thermal expansion is restored, the tightening device is not being clamped, but rather that a residual clearance is being maintained. Although in the majority of cases the adjusting step is obtained even with standard braking actions, the device has to be designed for the return stroke as described for the maximum braking action, which automatically results in a greater piston travel and a correspondingly higher energy consumption.